The invention relates to a gas valve unit for setting gas volumetric flows to a twin-circuit gas burner of a gas appliance, in particular a gas cooking appliance, wherein the gas valve unit has a gas inlet and two gas outlets.
In gas cooking appliances gas burners are frequently used, which have two concentrically disposed rings with gas outlet openings. During operation of the gas cooktop a ring of flame can burn at each of the rings with gas outlet openings. If the gas volumetric flows to both rings with gas outlet openings can be set separately from one another, said gas burners are referred to as twin-circuit gas burners. Twin-circuit gas burners generally have a greater maximum thermal output than conventional gas burners with just one ring of flame. Twin-circuit gas burners also have a particularly good spread between minimum thermal output and maximum thermal output. At maximum thermal output both rings of flame burn with the largest flames possible. At minimum thermal output only the smaller ring of flame burns with the smallest flames possible, while no gas flows out of the larger ring with flame outlet openings.
Gas valves for supplying twin-circuit gas valves have a gas inlet, with which the gas valve is connected to a main gas line of the gas cooking appliance. A first gas outlet of the gas valve opens into a first gas sub-line leading to the smaller ring with gas outlet openings. A second gas outlet is connected to a gas sub-line leading to the larger ring with gas outlet openings.
Twin-circuit gas valves have a single actuation element, which can be used to set both the gas flow to supply the first ring of flame and the gas flow to supply the second ring of flame. According to a standard model the completely closed position of the twin-circuit gas valve is followed immediately by the switching position for maximum output of both rings of flame. Further actuation of the operating element initially reduces the output of the larger ring of flame, until it is extinguished completely. The output of the smaller ring of flame is then reduced, until it reaches its minimum output. With this embodiment either the twin-circuit gas valve is completely closed or only the gas flow to the smaller ring with gas outlet openings is opened or the gas flow to both rings with gas outlet openings is opened, depending on the position of the actuation element. However provision is not made for closing the gas flow to the smaller ring with gas outlet openings, while the gas flow to the larger ring with gas outlet openings is open.
Known gas valve units for twin-circuit gas burners are generally embodied as plug valves, in which a valve plug is rotated in a valve housing by means of the actuation element. It has proven difficult to set a desired thermal output precisely and reproduce such a setting with such known valves.